package report

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/fraktal/mev-beta/tools/math-audit/internal/audit"
)

// WriteJSON writes the audit result as pretty JSON to the specified directory.
func WriteJSON(dir string, res audit.Result) (string, error) {
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return "", fmt.Errorf("create report dir: %w", err)
	}
	path := filepath.Join(dir, "report.json")
	payload, err := json.MarshalIndent(res, "", "  ")
	if err != nil {
		return "", fmt.Errorf("marshal report: %w", err)
	}
	if err := os.WriteFile(path, payload, 0o644); err != nil {
		return "", fmt.Errorf("write report: %w", err)
	}
	return path, nil
}

// WriteMarkdown renders a human-readable summary and writes it next to the JSON.
func WriteMarkdown(dir string, res audit.Result) (string, error) {
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return "", fmt.Errorf("create report dir: %w", err)
	}
	path := filepath.Join(dir, "report.md")
	content := GenerateMarkdown(res)
	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
		return "", fmt.Errorf("write markdown: %w", err)
	}
	return path, nil
}

// GenerateMarkdown returns a markdown representation of the audit result.
func GenerateMarkdown(res audit.Result) string {
	var b strings.Builder
	b.WriteString("# Math Audit Report\n\n")
	b.WriteString(fmt.Sprintf("- Generated: %s UTC\n", res.Summary.GeneratedAt.Format("2006-01-02 15:04:05")))
	b.WriteString(fmt.Sprintf("- Vectors: %d/%d passed\n", res.Summary.VectorsPassed, res.Summary.TotalVectors))
	b.WriteString(fmt.Sprintf("- Assertions: %d/%d passed\n", res.Summary.AssertionsPassed, res.Summary.TotalAssertions))
	b.WriteString(fmt.Sprintf("- Property checks: %d/%d passed\n\n", res.Summary.PropertySucceeded, res.Summary.PropertyChecks))

	if len(res.Vectors) > 0 {
		b.WriteString("## Vector Results\n\n")
		b.WriteString("| Vector | Exchange | Status | Notes |\n")
		b.WriteString("| --- | --- | --- | --- |\n")
		for _, vec := range res.Vectors {
			status := "✅ PASS"
			if !vec.Passed {
				status = "❌ FAIL"
			}

			var notes []string
			for _, test := range vec.Tests {
				if !test.Passed {
					notes = append(notes, fmt.Sprintf("%s (%.4f bps)", test.Name, test.DeltaBPS))
				}
			}
			if len(vec.Errors) > 0 {
				notes = append(notes, vec.Errors...)
			}
			noteStr := ""
			if len(notes) > 0 {
				noteStr = strings.Join(notes, "; ")
			}

			b.WriteString(fmt.Sprintf("| %s | %s | %s | %s |\n", vec.Name, vec.Exchange, status, noteStr))
		}
		b.WriteString("\n")
	}

	if len(res.PropertyChecks) > 0 {
		b.WriteString("## Property Checks\n\n")
		for _, check := range res.PropertyChecks {
			status := "✅"
			if !check.Passed {
				status = "❌"
			}
			if check.Details != "" {
				b.WriteString(fmt.Sprintf("- %s %s — %s\n", status, check.Name, check.Details))
			} else {
				b.WriteString(fmt.Sprintf("- %s %s\n", status, check.Name))
			}
		}
		b.WriteString("\n")
	}

	return b.String()
}